Closed-loop adjustment system and method for gap control and leveling of ultrasonic devices

ABSTRACT

An apparatus and method for leveling a bonding device and anvil in an assembly via a closed-loop control system is provided. The assembly includes an anvil, a bonding device positioned adjacent the anvil and configured to interact with the anvil to form the bonds on the web, and an actuator that enables adjustment of an orientation between the bonding device and the anvil. The assembly also includes a closed-loop control system configured to control operation of the actuator, with the closed-loop control system configured to monitor an operational parameter of the assembly indicative of interaction of the bonding device with the anvil, determine whether the bonding device is parallel or substantially parallel with the anvil based on the operational parameter, and when the bonding device is not parallel or substantially parallel with the anvil, cause the actuator to adjust the orientation between the bonding device and the anvil.

CROSS-REFERENCE TO RELATED APPLICATION

The present invention is a non-provisional of and claims priority toU.S. Provisional Patent Application Ser. No. 62/741,263, filed Oct. 4,2018, the disclosure of which is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

The present invention relates to disposable garments and morespecifically, to systems and methods for making disposable garments.More specifically, the invention relates to ultrasonic bonding ofgarment layers and to the control and adjustment of the spacing andangling between an ultrasonic horn and patterned anvil in an ultrasonicassembly.

Ultrasonic technology is used, among other technologies, to bondnon-woven fabric garment layers, as an alternative to (or to reduce theuse of) consumables such as adhesives or glue. Ultrasonic energy isconcentrated at specific bond points where frictional heat bondsnon-woven fabric of the garment layers. An ultrasonic bonding systemcontains at least one patterned anvil that communicates with at leastone ultrasonic horn. The patterned anvil contains a predeterminedpattern created by raised regions on the anvil. The ultrasonic horncontains an ultrasonic emitting assembly. Layers of non-woven fabric,which may or may not contain additional garment components, are passedbetween the patterned anvil and the ultrasonic horn. The layers contactthe raised pattern on the patterned anvil. While in contact with theraised pattern, the layers pass through an ultrasonic emission createdby the ultrasonic horn. The ultrasonic emission increases the vibrationsof the particles in the non-woven garment, thus increasing thetemperature of the particles in the non-woven garment. The increasedtemperatures of the garment particles in the multiple layers ofnon-woven fabric result in bonding of the multiple layers of non-wovenfabric along the raised patterns of the patterned anvil.

The ultrasonic horn should ideally be maintained at a constant andpredetermined distance from the layers of non-woven fabric over across-machine direction length of the ultrasonic horn. Methods tomonitor and control the constant and predetermined distance over thecross-machine direction length of the ultrasonic horn have typicallybeen performed manually by an operator loosening and tightening a seriesof bolts on the ultrasonic horn. The operator manually loosens thebolts, manually adjusts a gap, or distance, between the ultrasonic hornand the patterned anvil, and manually adjusts the level of theultrasonic horn with respect to the patterned anvil. However, thismethod often results in an ultrasonic horn placement where the distancebetween the ultrasonic horn and the patterned anvil is not ideal. As aresult of this non-ideal gap or distance, the layers of non-woven fabricwill experience varied bonding conditions over the cross-machinedirection length. Locations where the distance between the ultrasonichorn and patterned anvil may be less than ideal may result in a‘blow-out’ phenomenon in which in the ultrasonic energy creates a holethrough the layers of non-woven fabric. Locations where the distancebetween the ultrasonic horn and patterned anvil may be less than idealmay result in the layers of non-woven fabric not becoming bondedtogether.

Further, the leveling of the ultrasonic horn and the adjusting of thegap or distance between the ultrasonic horn and patterned anvil is not asingular event. Instead, the adjustment of the gap or distance requiresmultiple adjustments over the operation of the machine. Every time thegap or distance between the ultrasonic horn and patterned anvil isadjusted manually and/or the ultrasonic horn is leveled, the machine isunable to be run during the manual adjustment process.

Therefore, a need exists for an automated system and method foradjusting the gap, or distance, between the ultrasonic horn andpatterned anvil and for performing leveling of the ultrasonic hornand/or the anvil into a parallel arrangement. A need further exists forsuch gap adjustment and leveling to be performed while the machinecontinues to run, with such gap adjustment and leveling beingperiodically performed during operation of the machine.

BRIEF DESCRIPTION OF THE INVENTION

In accordance with one aspect of the invention, an apparatus for formingbonds on a web includes an anvil, a bonding device positioned adjacentthe anvil and configured to interact with the anvil to form the bonds onthe web, and an actuator that enables adjustment of an orientationbetween the bonding device and the anvil. The apparatus also includes aclosed-loop control system configured to control operation of theactuator, the closed-loop control system configured to monitor anoperational parameter of the apparatus indicative of interaction of thebonding device with the anvil, determine whether the bonding device isparallel or substantially parallel with the anvil based on theoperational parameter, and when the bonding device is not parallel orsubstantially parallel with the anvil, cause the actuator to adjust theorientation between the bonding device and the anvil.

In accordance with another aspect of the invention, a method forleveling a bonding device and anvil in an assembly via a closed-loopcontrol system is provided. The method includes monitoring anoperational parameter of the assembly indicative of interaction of thebonding device with the anvil and determining, based on the operationalparameter, whether the bonding device and the anvil are parallel orsubstantially parallel. The method also includes controlling an actuatorto adjust an orientation between the bonding device and the anvil whenthe bonding device and the anvil are determined to not be parallel orsubstantially parallel. The monitoring of the operational parameter andthe operation of the actuator to adjust the orientation between thebonding device and the anvil is performed via a closed-loop controlscheme.

These and other advantages and features will be more readily understoodfrom the following detailed description of preferred embodiments of theinvention that is provided in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate embodiments presently contemplated for carryingout the invention.

In the drawings:

FIG. 1 is a system view of a bonding assembly that includes aclosed-loop control system for leveling and gap adjustment between anultrasonic horn and patterned anvil, with the ultrasonic horn andpatterned anvil in a non-level or non-parallel arrangement, according toan embodiment of the invention.

FIG. 2 is a system view of the bonding assembly of FIG. 1 illustratingthe ultrasonic horn and patterned anvil in a level or parallelarrangement.

FIG. 3 is a system view of a bonding assembly that includes aclosed-loop control system for leveling and gap adjustment between anultrasonic horn and patterned anvil, with the ultrasonic horn andpatterned anvil in a non-level or non-parallel arrangement, according toanother embodiment of the invention.

FIG. 4 is a system view of the bonding assembly of FIG. 3 illustratingthe ultrasonic horn and patterned anvil in a level or parallelarrangement.

FIG. 5 is a system view of a bonding assembly that includes aclosed-loop control system for leveling and gap adjustment between anultrasonic horn and patterned anvil, with the ultrasonic horn andpatterned anvil in a non-level or non-parallel arrangement, according toanother embodiment of the invention.

FIG. 6 is a system view of the bonding assembly of FIG. 5 illustratingthe ultrasonic horn and patterned anvil in a level or parallelarrangement.

FIG. 7 is a graphical illustration of force value readings taken by theclosed-loop control system of FIGS. 5 and 6 over time at opposing sidesof the ultrasonic horn assembly and patterned anvil, indicating anon-parallel arrangement or non-level condition.

FIG. 8 is a graphical illustration of force value readings taken by theclosed-loop control system of FIGS. 5 and 6 over time at opposing sidesof the ultrasonic horn assembly and patterned anvil, indicating aparallel arrangement or level condition.

FIG. 9 is a flowchart illustrating a method for leveling an ultrasonichorn and anvil in an ultrasonic assembly via a closed-loop controlsystem, according to an embodiment of the invention.

FIG. 10 is a system view of the bonding assembly of FIGS. 1 and 2illustrating a gap adjustment between the ultrasonic horn and patternedanvil, according to another embodiment of the invention.

FIG. 11 is a block schematic diagram of multiple ultrasonic hornsoperably coupled with a single generator, useable with the bondingassembly of FIGS. 1 and 2, according to an embodiment of the invention.

DETAILED DESCRIPTION

Embodiments of the present invention provide for a method and apparatusfor leveling of the ultrasonic horn and/or patterned anvil in anultrasonic assembly into a parallel or substantially parallelarrangement and for adjusting the gap, or distance, between of theultrasonic horn and the anvil.

Although the disclosure hereof is detailed and exact to enable thoseskilled in the art to practice the invention, the physical embodimentsherein disclosed merely exemplify the invention which may be embodied inother specific structures. While the preferred embodiment has beendescribed, the details may be changed without departing from theinvention, which is defined in the specification.

With attention to FIGS. 1 and 2, a bonding apparatus or assembly 10 isillustrated, according to an embodiment of the invention. According toan exemplary embodiment, the bonding assembly 10 comprises an ultrasonicassembly that functions to ultrasonically form bonds on one or more webmaterials and/or elastics, and thus hereafter bonding assembly 10 isreferred to as ultrasonic assembly 10. It is recognized, however, thatthe bonding assembly 10 could alternatively be configured to performother types of bonding, including thermal or pressure bonding, forexample, and thus embodiments of the invention are not limited only toultrasonic bonding.

As shown in FIGS. 1 and 2, the ultrasonic assembly 10 comprises at leastone ultrasonic horn assembly 12 and at least one patterned anvil 14(hereinafter “anvil 14”), according to known constructions, along with aclosed-loop control system 16. The ultrasonic assembly 10 may be any ofa number of known ultrasonic bonding or welding systems, such as arotary anvil and an ultrasonic blade horn, also known as a sonotrode,which cooperate with each other to form bonds on one or more webmaterials and/or elastics (not shown) that is passed between theultrasonic horn assembly 12 and anvil 14. The ultrasonic horn assembly12 and anvil 14 are positioned in a spaced relationship relative to oneanother to facilitate ultrasonically bonding the web materials/elastics.During the bonding process, the web layers are exposed to an ultrasonicemission from the ultrasonic horn assembly 12 that causes the particlesin the web layers to vibrate. The ultrasonic emission or energy isconcentrated at specific bond points where frictional heat fuses the weblayers together without the need for consumable adhesives.

The ultrasonic assembly 10 may include a single ultrasonic horn assembly12 in communication with a single anvil 14, as shown in FIGS. 1 and 2.Alternatively, multiple ultrasonic horn assemblies 12 may be incommunication with a single anvil 14, a single ultrasonic horn assembly12 may be in communication with multiple anvils 14, or multipleultrasonic horn assemblies 12 may be in communication with multipleanvils 14 in various arrangements.

As shown in FIGS. 1 and 2, the ultrasonic horn assembly 12 comprises anassembly holder 18 and an ultrasonic stack 20 of components, with theholder 18 mechanically coupled to the ultrasonic stack 20. According toan exemplary embodiment, the ultrasonic stack 20 includes a converter22, a booster 24, and a horn 26. The converter 22 receives a highfrequency AC current from the generator 30 indicative of a desiredoperation of the ultrasonic horn assembly 12 and transforms the signalinto a mechanical vibration or ultrasonic emission. The ultrasonicemission is amplified via booster 24 and is transmitted to the horn 26.Based on the interaction of the horn 26 and anvil 14, the ultrasonicemission or energy is concentrated at specific bond points, wherefrictional heat fuses the web layers together. Booster 24 may be omittedin alternative embodiments.

The closed-loop control system 16 is configured to determine a levelingcondition of the ultrasonic horn assembly 12 (i.e., of horn 26) withrespect to the anvil 14. As can be seen in FIGS. 1 and 2, in a non-levelcondition (FIG. 1), a distance D1 between the horn 26 and anvil 14 at afirst location is different from a distance D2 between the horn 26 andanvil 14 at a second location, while when in a level condition (FIG. 2),the distances D1, D2 are equal or substantially equal to eachother—i.e., a distance D3, such that the facing surfaces 27, 29 of thehorn 26 and anvil 14 are parallel (i.e., level) or substantiallyparallel with one another. As used herein, “substantially parallel”means parallel to within +/−5 degrees.

In the illustrated embodiment, closed-loop control system 16 comprises aprogrammable logic controller (PLC) 28, a generator 30, and an actuator32. The elements/components of the closed-loop control system 16 are inoperable communication with each other, with the generator 30 inoperable communication with the PLC 28 along a generator/PLCcommunication 34, the generator 30 in operable communication with theultrasonic horn assembly 12 along a high frequency cable orcommunication 36, and the PLC 28 in operable communication with theactuator 32 along a PLC/actuator communication 38. The generator 30 andPLC 28 function to monitor one or more operational parameters of theultrasonic assembly 10 indicative of interaction of the ultrasonic hornassembly 12 with the anvil 14 and determine a condition of theultrasonic horn assembly 12, such as a leveling condition of theultrasonic horn assembly 12 with respect to the anvil 14. The PLC 28then generates and transmits control signals to the actuator 32 based onthe determination of the leveling condition, with the control signalscontrolling operation of actuator 32.

The actuator 32 of the closed-loop control system is coupled to theassembly holder 18 to provide for movement and/or rotation thereof—andto thereby also cause movement or rotation of the ultrasonic stack 20.The actuator 32 comprises a drive 40, such as a servo motor, thatoperates to cause movement of an adjustment mechanism 42—with the drive40 coupled to the adjustment mechanism 42 via a linkage system 44. Theadjustment mechanism 42 that is driven by drive 40 may be any of anumber of suitable mechanisms, such as an arrangement of a slidemechanism 46 and channel 48 (as illustrated in FIGS. 1 and 2), a rackand pinion device, rocker assembly, or threaded rod and plate assembly,according to embodiments of the invention. The repositioning of theultrasonic stack 20 via operation of actuator 32 serves to adjust theorientation of the horn 26 relative to the anvil 14, so as to providefor leveling of the horn 26 and the anvil 14.

According to embodiments of the invention, operation of the actuator 32to adjust positioning of the ultrasonic stack 20 is controlled based ona determination of a leveling condition of the horn 26 with respect tothe anvil 14. The determination of the leveling condition of the horn 26and anvil 14 is performed by the PLC 28 based on the measurement of oneor operational parameters associated with operation of the ultrasonichorn assembly 12. According to various embodiments, the operationalparameter(s) may be measured directly by the generator 30, by a separatesensor included on cabling connecting the generator 30 to the ultrasonichorn assembly, or by other external sensors positioned on the horn oranvil.

In one embodiment, the generator 30 directly measures power valuesassociated with, or correlated to, the interaction of the horn 26 withthe anvil 14. That is, in operation of ultrasonic horn assembly 12,command signals are initially provided to converter 22 (from generator30) that are indicative of a desired ultrasonic emission to be output byhorn 26 for forming bonds on the web layer(s) positioned between thehorn 26 and the anvil 14, with the converter 22 and (optional) booster24 transforming the received command signals into a final output to thehorn 26 that causes output of the ultrasonic emission. The resultingpower or energy that is transferred to the web layer(s) for theformation of bonds is dependent on the arrangement of the horn 26relative to the anvil 14 and may be measured by the generator 30 basedon the outgoing current demanded by the horn 26.

In operation, the generator 30 acquires a plurality of power readingsthat are indicative of the operation of the ultrasonic horn assembly 12and of a leveling condition of the horn 26 with respect to the anvil 14.The generator 30 provides those measurements to the PLC 28 forcomparison thereof and determination of the leveling condition. Morespecifically, the PLC 28 compares a plurality of power readings in orderto identify a maximum power value that corresponds to a level orparallel arrangement between the horn 26 and the anvil 14.

In performing a method for leveling the horn 26 relative to the anvil14, the generator 30 begins by measuring a first power value with thehorn 26 at a first position or orientation and providing thosemeasurements to the PLC 28. Subsequent to the measurement, the PLC 28functions to operate the actuator 32 to reorient the horn 26 relative tothe anvil 14—with the actuator 32 causing the horn 26 to rotate in afirst direction and to a second position. Upon reorienting the horn 26to the second position, the generator 30 measures a second power valueand provides those measurements to the PLC 28. The PLC 28 then comparesthe second power value to the first power value and, if the second powervalue is greater than the first power value, the PLC 28 operates theactuator 32 to reorient the horn 26 relative to the anvil 14—with theactuator 32 causing the horn 26 to continue rotating in the firstdirection and to a third position. This sequence of power measurementsand rotation of horn 26 in the first direction continues until themeasured power value at a new horn position is less than the measuredpower value at the previous horn position. When the new power value isless than the previous power value, PLC 28 operates the actuator 32 torotate the horn 26 in a second direction (opposite the first direction),to return the horn 26 to the position where the larger power value wasmeasured.

Conversely, if upon reorienting the horn 26 to the second position, themeasured second power value is less than the first power value, the PLC28 operates the actuator 32 to successively rotate the horn in thesecond direction to one or more new positions. At each positiongenerator 30 monitors a new power value and provides those measurementsto the PLC 28. The PLC 28 compares each new power value to the previouspower value. As long as the new power value is greater than the previouspower value, PLC 28 continues to rotate the horn in the seconddirection. If the new power value is less than the previous power value,PLC 28 either maintains the horn 26 in the current position or operatesthe actuator 32 to rotate the horn 26 in the first direction, to returnthe horn 26 to the position where the larger power value was measured.This larger power value is referred to hereafter as the maximum powervalue.

In general, during a leveling or paralleling operation the PLC 28 willgenerate commands that operate the actuator 32 to continue to rotate thehorn 26 in the same direction as long as a subsequent power valuereading/measurement is greater than the previous power valuereading/measurement, in order to search for a position or orientation ofthe horn 26 that provides maximum power—i.e., a level or parallelposition. Upon a subsequent power value reading/measurement being lessthan the previous power value reading/measurement, the PLC 28 will flagthe previous position as the level or parallel position and cause thehorn 26 to stay in the current orientation or rotate back to the levelor parallel position at which the maximum power value was measured. Inan instance where the previous and subsequent power values are equal,PLC 28 may cause the horn 26 to stay in the current orientation.Accordingly, adjustment of the horn 26 from a non-level position(FIG. 1) to a position where surface 27 of the horn 26 is level/parallelwith the facing surface 29 of the anvil 14 (FIG. 2) may be achieved.

While operation of the generator 30 is described above as measuringpower values from the ultrasonic horn assembly 12, it is recognized thatgenerator 30 could alternatively measure other operational parameters,including capacitance, frequency, or amplitude, as non-limitingexamples, in order to determine the leveling condition. Determination ofthe leveling condition with measurement of any of the parameters wouldbe similar to the method described above, with the PLC 28 comparing aplurality of readings in order to identify a specified parameter value(e.g., maximum value) that corresponds to a level or parallelarrangement between the horn 26 and the anvil 14.

Referring still to FIGS. 1 and 2, according to another embodiment, adedicated induction sensor 50 (shown in phantom) positioned on orintegrated into the high frequency cable 36 is used to monitor operationof the ultrasonic horn assembly 12 rather than the generator 30performing this function. In such an embodiment, generator 30 stilloperates to provide command signals to converter 22 that are indicativeof a desired ultrasonic emission to be output by horn 26 for formingbonds on the web layer(s) positioned between the horn 26 and the anvil14, with the converter 22 and (optional) booster 24 transforming thereceived command signals into a final output to the horn 26 that causesoutput of the ultrasonic emission. However, the generator 30 is notconfigured to directly measure or monitor power signals fed back fromthe ultrasonic horn assembly 12, and thus a separate induction sensor 50is employed to monitor operation of the ultrasonic horn assembly 12.Such an induction sensor 50 may be used to retrofit an existingultrasonic assembly 8 (and generator 30) to enable the assembly 8 toperform a determination of the leveling condition of the horn 26 withrespect to the anvil 14.

In operation, induction sensor 50 measures electrical current values onthe high frequency cable 36 in order to identify a power reading/valueindicative of the interaction of the horn 26 with the anvil 14, so as toprovide for a determination of the leveling condition of the horn 26with respect to the anvil 14. The measured current values—andsubsequently derived power values—are provided to the PLC 28, wherecomparison of the power values is performed in order to determine theleveling condition. That is, the PLC 28 compares a plurality of powerreadings in order to identify a maximum current value that correspondsto a level or parallel arrangement between the horn 26 and the anvil 14.

The method for leveling the horn 26 relative to the anvil 14 usinginduction sensor 50 is similar to that described above where powervalues are measured directly by generator 30. The induction sensor 50measures a first current/power value with the horn 26 at a firstposition or orientation and provides those measurements to the PLC 28.Subsequent to the measurement, the PLC 28 functions to operate theactuator 32 to thereby reorient the ultrasonic horn 26 relative to theanvil 14—with the actuator 32 causing the horn 6 to rotate in a firstdirection and to a second position. Upon reorienting of the ultrasonichorn assembly 12 to the second position, the induction sensor 50measures a second current/power value and provides those measurements tothe PLC 28. The PLC 28 then compares the second current/power value tothe first current/power value and, if the second current/power value isgreater than the first current/power value, the PLC 28 operates theactuator 32 to reorient the ultrasonic horn 26 relative to the anvil14—with the actuator 32 causing the horn 6 to continue rotating in thefirst direction and to a third position. Conversely, if the secondcurrent/power value is less than the first current/power value, the PLC28 then determines that the previous orientation of surface 27 of thehorn 26 relative to the facing surface 29 of the anvil 14 was closer toparallel. The PLC 28 thus operates the actuator 32 to reorient the horn26 relative to the anvil 14—with the actuator 32 causing the horn 26 torotate in a second direction (opposite the first direction) and back tothe first position.

The embodiments described above and shown in FIGS. 1 and 2 are directedto a system and method for adjusting and reorienting the ultrasonic hornassembly 12 in order to level the horn 26 and anvil 14. FIGS. 3 and 4depict an alternative embodiment that includes a system and method foradjusting and reorienting the anvil 14 in order to level the horn 26 andanvil 14 using a closed-loop control system 16 that is in operablecommunication with an actuator 52 that provides for movement and/orrotation of the anvil 14. The actuator 52 comprises a drive 54, such asa servo motor, that operates to cause movement of an adjustmentmechanism 56—with the drive 54 coupled to the adjustment mechanism 56via a linkage system 58. The adjustment mechanism 56 may be any of anumber of suitable mechanisms, such as an arrangement of a slidemechanism and channel (as illustrated in FIGS. 3 and 4), a rack andpinion device, rocker assembly, or threaded rod and plate assembly,according to embodiments of the invention. The repositioning of theanvil 14 via operation of actuator 52 serves to adjust the orientationof the anvil 14 relative to the horn 26, so as to provide for levelingof the horn 26 and the anvil 14.

According to embodiments of the invention, the actuator 52 is controlledto adjust positioning of the anvil 14 based on a determination of aleveling condition of the anvil 14 with respect to the horn 26. Asdescribed above with regard to the embodiments in FIGS. 1 and 2, thegenerator 30 may measure power values indicative of the interaction ofthe horn 26 with the anvil 14 (or capacitance, frequency, or amplitude)or, alternatively, induction sensor 50 may measure current/power valuesindicative of the interaction of the horn 26 with the anvil 14, in orderto provide for a determination of the leveling condition of the horn 26and the anvil 14. The measured power/current values are provided to thePLC 28, where comparison of the power/current values is performed inorder to determine the leveling condition.

The method for leveling the anvil 14 relative to the horn 26 using themeasured power or current values is essentially identical to thosedescribed above. The position and orientation of the anvil 14 isincrementally adjusted by actuator 52 responsive to a plurality ofcomparisons of the power/current readings by the PLC 28, until the PLC28 identifies a maximum power/current value that corresponds to a levelor parallel arrangement between the horn 26 and the anvil 14.

Referring now to FIGS. 5 and 6, according to another embodiment, one ormore external sensors 60, 62 may be provided in order to measure one ormore operational parameters associated with operation of a bondingassembly 10, for purposes of performing leveling in the assembly. In oneembodiment, the external sensors 60, 62 are used in an ultrasonicassembly 10 (as described below), but it is recognized that the externalsensors 60, 62 could be utilized for performing leveling in otherbonding assemblies, such as a thermal bonding assembly or pressurebonding assembly.

In the embodiment illustrated in FIGS. 5 and 6, one or more externalsensors 60, 62 are provided on either the horn or anvil in order tomeasure one or more operational parameters associated with operation ofthe ultrasonic assembly. The external sensors 60, 62 may be any of anumber of types of known sensors, including load cells, optical sensors,EMF sensors, strain gauges, temperature sensors, or sonar sensors, forexample. For purposes of explanation, the embodiment discussed herebelow is described with two sensors 60, 62 being in the form of loadcells (hereinafter “load cells 60, 62”) that acquire a forcemeasurement. Additionally, while the load cells 60, 62 are illustratedas being incorporated into horn 26, it is recognized that the load cells60, 62 could alternatively be incorporated into anvil 14. Yet otherembodiments may include a single external sensor or three or moresensors.

According to an exemplary embodiment, a pair of load cells 60, 62 isprovided on horn 26—with a first load cell 60 in close proximity to afirst lateral side of the horn 26 and the second load cell 62 in closeproximity to a second lateral side of the horn 26—such that the loadcells 60, 62 are generally on opposing sides of the horn 26. With theload cells 60, 62 positioned in such a manner, the load cells 60, 62operate to measure a force value at each of the opposing sides of thehorn 26—hereinafter referred to as F1 and F2.

In operation, the load cells 60, 62 measure force values F1 and F2indicative of the interaction of the ultrasonic horn 26 with the anvil14 in order to provide for a determination of the leveling condition ofthe horn 26 with respect to the anvil 14. The measured force values F1and F2 are provided to the PLC 28, where comparison of the force valuesF1 and F2 is performed in order to determine the leveling condition.

The method for leveling the ultrasonic horn 26 relative to the anvil 14using measured force values begins with the load cells 60, 62 measuringforce values F1, F2 with the horn 26 at a first position or orientationand providing these measurements to the PLC 28. Subsequent to themeasurements, the PLC 28 then compares the force values F1, F2 todetermine if the values are equal or within a predetermined standarddeviation of one another. If the force values F1, F2 are equal (orwithin a predetermined standard deviation of one another), the PLC 28determines that the horn 26 and anvil 14 are in a level or parallelarrangement, and thus no adjustment of the horn 26 is required.Conversely, if the force values F1, F2 are not equal (or within apredetermined standard deviation of one another), the PLC 28 determinesthat the horn 26 and anvil 14 are in a non-level arrangement and thusoperates the actuator 32 to reorient the horn 26 relative to the anvil14—with the actuator 32 causing the horn 26 to rotate in a firstdirection, from a first position to a second position.

Upon the horn 26 rotating to the second position, the load cells 60, 62again measure force values F1, F2 and provide these measurements to thePLC 28. The PLC 28 then compares these force values F1, F2 to determineif the values are equal or within a predetermined standard deviation ofone another. If the force values F1, F2 are still not equal (or within apredetermined standard deviation of one another), the PLC 28 determinesthat the horn 26 and anvil 14 are in a non-level arrangement andoperates the actuator 32 to reorient the horn 26 relative to the anvil14—with the actuator 32 causing the horn 26 to continue to rotate in thefirst direction, from the second position to a third position. The PLC28 continues to operate actuator 32 in this manner until it isdetermined that the values F1, F2 are equal or within a predeterminedstandard deviation of one another—with the horn 26 and anvil 14 in alevel or parallel arrangement

Referring to FIG. 7, a graphic analysis of the force value readings F1,F2 over time is shown for purposes of illustration. During the time span64, the force values F1 and F2 are the same or within a predeterminedsuitable standard deviation. Force readings having an equal value orthat are within a predetermined suitable standard deviation indicatesthat the ultrasonic horn 26 is level with respect to the anvil 14. At atransition point 66, the force value for F1 drops—indicating a distanceD1 separation between the ultrasonic horn 26 and the anvil 14. The dropin the force value F1 is indicated by the graphic illustration sectiondrop 68. Additionally, at a transition point 66, the force value for F2rises—indicating a distance D2 separation between the ultrasonic horn 26and the anvil 14. The rise in the force value F2 is indicated by thegraphic illustration section rise 70. The graphical readings of F1 andF2, as indicated at 68 and 70, indicate the ultrasonic horn 26 is notlevel with respect to the anvil 14, as the force values F1, F2 are notequal and not within a predetermined suitable standard deviation.Referring to FIG. 8, a graphic analysis of the force value readings F1,F2 over time illustrates that the ultrasonic horn 26 is level withrespect to the anvil 14. During the time span 72, the force values F1and F2 are thus the same or within a predetermined standard deviation.

Referring now to FIG. 9, and with continued reference to FIGS. 1-6, amethod 74 for leveling an ultrasonic horn 26 and anvil 14 in anultrasonic assembly 10 via a closed-loop control system 16 is shown,according to an embodiment of the invention.

The method 74 begins at STEP 75 with the monitoring of one or moreoperational parameters of the ultrasonic assembly 10. According toembodiments of the invention, the measurements may be acquired viadirect monitoring, measurement, or calculation by the generator 30, byan induction sensor 50 positioned on (or spliced into) the highfrequency cable 36 connecting the generator 30 and ultrasonic hornassembly 12, or by external sensor(s) 60, 62 integrated with the horn 26or anvil 14. The operational parameters monitored by the generator 30may comprise one of power, frequency, amplitude, or charge/capacitance,as non-limiting examples. The operational parameter measured by theinduction sensor 50 may comprise current. The operational parametersmeasured by the external sensors 60, 62 may comprise force, distance(between the horn and anvil), or temperature, as non-limiting examples.

At STEP 76, the PLC 28 causes the actuator 32 to iteratively rotate thehorn 26 (or anvil 14 in an alternative embodiment) in a first direction.The operational parameter is measured again at STEP 77.

At STEP 78, a determination is made as to whether the horn 26 and anvil14 are in an optimized parallel or level arrangement based on themonitored operational parameters acquired at STEP 75 and STEP 77. ThePLC 28 receives the operational parameters and performs an analysisthereof via a comparison of the operational parameters in order todetermine the leveling condition.

In an embodiment where the acquired operational parameter comprisespower readings, acquired either via generator 30 directly or viainduction sensor 50, STEP 78 includes the PLC 28 functioning to operatethe actuator 32 to iteratively reorient the ultrasonic horn 26 relativeto the anvil 14 until an optimized horn and anvil orientation isidentified. The identification of the optimized orientation is obtainedvia the PLC 28 causing the actuator 32 to iteratively rotate the horn 26in a first direction and acquiring updated power readings after eachrotation. The PLC 28 compares power readings after each rotation and,when a subsequent power value reading is greater than the immediatelypreceding power reading, the PLC 28 will determine that facing surfaces27, 29 of the horn 26 and anvil 14 are not in an optimized orientationor parallel/level relative to one another (as indicated at 80). The PLC28 will then cause the actuator 32 to continue to rotate the horn 26 inthe first direction at STEP 76—with the method then looping back to STEP77 for further monitoring of power values.

In the event that a subsequent power reading that is less than theimmediately preceding power reading, the PLC 28 may take one of twoactions. In one embodiment, the PLC 28 identifies the current horn/anvilorientation as corresponding to an optimized orientation (as indicatedat 82). Thereafter, the current horn/anvil orientation is flagged as anoptimized level condition or parallel orientation at STEP 86.Alternatively, upon determining that a subsequent power reading that isless than the immediately preceding power reading, method 74 may proceedto optional STEP 84 wherein the PLC 28 controls the actuator 32 torotate the horn 26 in a second direction (opposite the first direction)to return to the previous position. The resulting horn or anvil positionis flagged as an optimized level condition or parallel orientation atSTEP 86. Thereafter, the method loops back to STEP 77 for furthermonitoring of power values.

In an embodiment where the acquired operational parameter is anoperational parameter (e.g., force or distance readings) acquired viaexternal sensors 60, 62, method 74 includes the PLC 28 functioning tooperate the actuator 32 to iteratively reorient the ultrasonic horn 26relative to the anvil 14 until sensor readings from generally opposingsides of the horn 26 (or anvil 14) are equal or within a predeterminedstandard deviation. If the force/distance values from opposing sides ofthe horn 26 or anvil 14 are equal or within a predetermined standarddeviation of one another, the PLC 28 determines that the horn 26 andanvil 14 are in an optimized level or parallel arrangement (as indicatedat 82) and flags the orientation as optimized at STEP 86. The PLC 28thus does not send command signals to the actuator 32, and the methodloops back to STEP 77 for further monitoring of power values.Conversely, if the force/distance values from opposing sides of the horn26 or anvil 14 are not equal or within a predetermined standarddeviation of one another, the PLC 28 determines that the horn 26 andanvil 14 are in a non-level arrangement (as indicated at 80) and thuscauses the actuator 32 to reorient the ultrasonic horn 26 relative tothe anvil 14 at STEP 76 and continue to monitor force/distance values atSTEP 77.

While embodiments of the invention described above are directed to anultrasonic assembly 10 and closed-loop system 16 for leveling of thehorn 26 and anvil 14, it is recognized that the closed-loop controlsystem 16 described above may also be utilized to monitor and adjust agap between the horn 26 and anvil 14, according to another embodiment.That is, a closed-loop control system 16 may be employed for performingboth gap control and leveling in the ultrasonic assembly 10.

Referring now to FIG. 10, the ultrasonic assembly 10 is illustratedwhere closed-loop control system 16 operates to perform a gap adjustmentbetween the horn 26 and the anvil 14. In performing such a gapadjustment, the generator 30 acquires a plurality of operationalparameter measurements that are indicative of the operation of theultrasonic assembly 10 and of a gap or distance 86 of the horn 26 fromthe anvil 14. The generator 30 provides those measurements to the PLC 28for comparison thereof and determination of the gap/distance 86. Theoperational parameter measurements may comprise power, capacitance,frequency, or amplitude as non-limiting examples. In one exemplaryembodiment, the PLC 28 compares a plurality of power readings in orderto maintain a predetermined target power value that corresponds to adesired gap between the horn 26 and the anvil 14.

As with performing leveling in the ultrasonic assembly 10, the generator30 may measure power values indicative of the interaction of the horn 26with the anvil 14 (or capacitance, frequency, or amplitude) or,alternatively, induction sensor 50 may measure current/power valuesindicative of the interaction of the horn 26 with the anvil 14, in orderto provide for a determination of an ideal gap distance between the horn26 and the anvil 14. The measured power/current values are provided tothe PLC 28, where comparison of the power/current values is performed inorder to determine the ideal gap distance. The position of the horn 26,i.e., distance thereof from the anvil 14, is incrementally adjusted viaoperation of actuator 32 responsive to a plurality of comparisons of thepower/current readings by the PLC 28 (such as from a distance D1, to adistance D2, to a distance D3) until the PLC 28 achieves a predeterminedtarget value that corresponds to an ideal gap distance between the horn26 and the anvil 14. That is, actuator 32 moves ultrasonic horn assembly12 (i.e., horn 26) in a direction 88 until a gap/distance 86 is set thatcorresponds with the target power/current value.

It is recognized that embodiments of the present invention, includingthe method 74 shown and described in FIG. 9, may be implemented isvarious types of ultrasonic assemblies. In one embodiment, and as shownin FIG. 11, an ultrasonic assembly may be provided in which a singlegenerator 30 may be used to gather power data from multiple ultrasonichorns 26 (associated with one or more anvils 14) and pass such data to aPLC 28 to determine a leveling condition of the horns. In such anembodiment, a switching device 90 is coupled between the generator 30and the ultrasonic horns 26 that is operable to selectively transmitpower (for example) from each of the respective ultrasonic horns 26 tothe generator 30, to enable power measurement for each of the horns 26.

Beneficially, embodiments of the invention thus provide a closed-loop,automated apparatus and method for adjusting the gap, or distance,between the ultrasonic horn and the patterned anvil and/or for levelingor paralleling the ultrasonic horn and the patterned anvil relative toone another. The automated gap control and leveling system reduces thedependency on manual gap control and/or leveling of the ultrasonic hornand anvil. The automated gap control and leveling system also providesfor gap control and/or leveling adjustments to be made while theultrasonic assembly continues to run. The automated gap control andleveling system further provides for continued measurement of the gapdistance and leveling condition between the ultrasonic horn andpatterned anvil and adjusts the gap and/or leveling based upon themeasurement results. Still further, the automated gap control andleveling system provides for gap control and/or leveling adjustments tobe made due to a change in the operating speed of the manufacturingmachine on which it operates, due to thermal growth of the ultrasonichorn, and/or due to material thickness of the web material or objectsubject to the ultrasonic frequency.

Therefore, according to one embodiment of the invention, an apparatusfor forming bonds on a web includes an anvil, a bonding devicepositioned adjacent the anvil and configured to interact with the anvilto form the bonds on the web, and an actuator that enables adjustment ofan orientation between the bonding device and the anvil. The apparatusalso includes a closed-loop control system configured to controloperation of the actuator, the closed-loop control system configured tomonitor an operational parameter of the apparatus indicative ofinteraction of the bonding device with the anvil, determine whether thebonding device is parallel or substantially parallel with the anvilbased on the operational parameter, and when the bonding device is notparallel or substantially parallel with the anvil, cause the actuator toadjust the orientation between the bonding device and the anvil.

According to another embodiment of the invention, a method for levelinga bonding device and anvil in an assembly via a closed-loop controlsystem is provided. The method includes monitoring an operationalparameter of the assembly indicative of interaction of the bondingdevice with the anvil and determining, based on the operationalparameter, whether the bonding device and the anvil are parallel orsubstantially parallel. The method also includes controlling an actuatorto adjust an orientation between the bonding device and the anvil whenthe bonding device and the anvil are determined to not be parallel orsubstantially parallel. The monitoring of the operational parameter andthe operation of the actuator to adjust the orientation between thebonding device and the anvil is performed via a closed-loop controlscheme.

According to yet another embodiment of the invention, an apparatus forforming bonds on a web includes an anvil, a bonding device positionedadjacent the anvil and configured to interact with the anvil to form thebonds on the web, and an actuator that enables adjustment of a spacingbetween the bonding device and the anvil. The apparatus also includes aclosed-loop control system configured to control operation of theactuator. The closed-loop control system is configured to monitor anoperational parameter indicative of interaction of the bonding devicewith the anvil, compare the operational parameter to a predeterminedtarget value, and when the operational parameter does not match thepredetermined target value, cause the actuator to move one of thebonding device and the anvil to adjust the spacing between the bondingdevice and the anvil. The closed-loop control system is configured tocompare a plurality of operational parameters to the predeterminedtarget value and cause the actuator to incrementally adjust a positionof one of the bonding device and the anvil to adjust the spacing betweenthe bonding device and the anvil. The position of one of the bondingdevice and the anvil is adjusted until the monitored operationalparameter matches the predetermined target value. In one embodiment thebonding device is an ultrasonic horn. In one embodiment the operationalparameter comprises a power value.

While the invention has been described in detail in connection with onlya limited number of embodiments, it should be readily understood thatthe invention is not limited to such disclosed embodiments. Rather, theinvention can be modified to incorporate any number of variations,alterations, substitutions or equivalent arrangements not heretoforedescribed, but which are commensurate with the spirit and scope of theinvention. Additionally, while various embodiments of the invention havebeen described, it is to be understood that aspects of the invention mayinclude only some of the described embodiments. Accordingly, theinvention is not to be seen as limited by the foregoing description, butis only limited by the scope of the appended claims.

What is claimed is:
 1. An apparatus for forming bonds on a web, theapparatus comprising: an anvil; a bonding device positioned adjacent theanvil and configured to interact with the anvil to form the bonds on theweb; an actuator that enables adjustment of an orientation between thebonding device and the anvil; a closed-loop control system configured tocontrol operation of the actuator, the closed-loop control systemconfigured to: monitor an operational parameter of the apparatusindicative of interaction of the bonding device with the anvil;determine whether the bonding device is parallel or substantiallyparallel with the anvil based on the operational parameter; and when thebonding device is not parallel or substantially parallel with the anvil,cause the actuator to adjust the orientation between the bonding deviceand the anvil.
 2. The apparatus of claim 1 wherein the bonding devicecomprises an ultrasonic horn.
 3. The apparatus of claim 2 wherein theclosed-loop control system is configured to: determine a plurality ofpower values associated with interaction of the ultrasonic horn with theanvil, with a respective power value of the plurality of power valuesbeing determined for each of a plurality of orientations of theultrasonic horn relative to the anvil; and cause the actuator toiteratively adjust the orientation between the ultrasonic horn and theanvil between each determining of successive power values.
 4. Theapparatus of claim 3 wherein the closed-loop control system isconfigured to: compare each successive pair of power values; identify amaximum power value associated with interaction of the ultrasonic hornwith the anvil from the comparison of each successive pair of powervalues; and identify the orientation of the ultrasonic horn and theanvil at which the maximum power value was measured or determined as anorientation at which the ultrasonic horn is parallel or substantiallyparallel with the anvil.
 5. The apparatus of claim 4 wherein theclosed-loop control system is configured to: compare a first power valueof a pair of successive power values to a second power value of the pairof successive power values; cause the actuator to rotate one of theultrasonic horn and the anvil in a first direction if the second powervalue is greater than the first power value; and cause the actuator torotate one of the ultrasonic horn and the anvil in a second directionopposite the first direction if the second power value is less than thefirst power value; wherein iterative rotation of one of the ultrasonichorn and the anvil based on the comparison of the first power value tothe second power value positions the ultrasonic horn parallel orsubstantially parallel with the anvil.
 6. The apparatus of claim 3wherein the closed-loop control system comprises: a generator inoperable communication with the ultrasonic horn, via a cable, to causethe ultrasonic horn to output an ultrasonic emission; and a programmablelogic controller (PLC) in operable communication with the generator andwith the actuator, the PLC configured to control operation of theactuator.
 7. The apparatus of claim 6 wherein the generator isconfigured to: determine the plurality of power values; and provide theplurality of power values to the PLC.
 8. The apparatus of claim 6further comprising an induction sensor positioned on or spliced into thecable, the induction sensor configured to: measure the plurality ofpower values; and provide the plurality of power values to the PLC. 9.The apparatus of claim 1 further comprising one or more sensorspositioned on or integrated with one of the bonding device and theanvil, the one or more sensors configured to measure the operationalparameter.
 10. The apparatus of claim 9 wherein the one or more sensorscomprises a pair of load cells positioned on or integrated with one ofthe bonding device and the anvil and positioned at opposing sidesthereof, the pair of load cells configured to measure a first forcevalue at a first location and measure a second force value at a secondlocation.
 11. The apparatus of claim 10 wherein the closed-loop controlsystem is configured to: determine that the bonding device is parallelor substantially parallel with the anvil when the first force value isequal to the second force value or is within a predetermined standarddeviation of the second force value; and determine that the bondingdevice is not parallel or substantially parallel with the anvil when thefirst force value is not equal to the second force value and is notwithin the predetermined standard deviation of the second force value.12. The apparatus of claim 1 wherein the actuator is operatively coupledto either the bonding device or the anvil to selectively adjust theorientation thereof.
 13. The apparatus of claim 1 wherein the actuatoris configured to adjust a gap between the bonding device and the anvil;and wherein the closed-loop control system is configured to cause theactuator to adjust the gap between the bonding device and the anvilbased on the operational parameter.
 14. A method for leveling a bondingdevice and anvil in an assembly via a closed-loop control system, themethod comprising: monitoring an operational parameter of the assemblyindicative of interaction of the bonding device with the anvil;determining, based on the operational parameter, whether the bondingdevice and the anvil are parallel or substantially parallel; and whenthe bonding device and the anvil are determined to not be parallel orsubstantially parallel, controlling an actuator to adjust an orientationbetween the bonding device and the anvil; wherein the monitoring of theoperational parameter and the operation of the actuator to adjust theorientation between the bonding device and the anvil is performed via aclosed-loop control scheme.
 15. The method of claim 14 wherein thebonding device comprises an ultrasonic horn, and wherein monitoring theoperational parameter comprises measuring a plurality of power valuesindicative of interaction of the ultrasonic horn with the anvil, theplurality of power values measured at differing orientations between theultrasonic horn and the anvil.
 16. The method of claim 15 whereinadjusting the orientation between the ultrasonic horn and the anvilcomprises iteratively adjusting the orientation between the ultrasonichorn and the anvil until a maximum power value is obtained.
 17. Themethod of claim 16 wherein determining whether the ultrasonic horn andthe anvil are parallel or substantially parallel comprises: comparingsuccessive pairs of power values from the plurality of power values;identifying the maximum power value from the comparison of eachsuccessive pair of power values; and identifying the orientation of theultrasonic horn and the anvil at which the maximum power value wasmeasured as an orientation at which the ultrasonic horn is parallel orsubstantially parallel with the anvil.
 18. The method of claim 14wherein monitoring the operational parameter comprises measuring forcevalues indicative of interaction of the ultrasonic horn with the anvil,the force values measured by a pair of load cells positioned on orintegrated with one of the bonding device and the anvil and comprising:a first force value measured at a location on a first side of the one ofthe bonding device and the anvil; and a second force value measured at alocation on a second side of the one of the bonding device and theanvil.
 19. The method of claim 18 wherein determining whether thebonding device and the anvil are parallel or substantially parallelcomprises: determining that the bonding device is parallel orsubstantially parallel with the anvil when the first power value isequal to the second power value or is within a predetermined standarddeviation of the second power value; and determining that the bondingdevice is not parallel or substantially parallel with the anvil when thefirst power value is not equal to the second power value and is notwithin the predetermined standard deviation of the second power value.20. The method of claim 14 wherein adjusting the orientation between thebonding device and the anvil comprises one of adjusting the orientationof the bonding device and adjusting the orientation of the anvil.